In the peeling and cleaning of food products that are typically vegetables and fruits, food processing machines utilizing rotating rollers that abrade the food product to peel, clean or wash the food product are commonly used. Each abrasive roller peeling and cleaning machine utilizes several abrasive elongate rollers grouped in a circle or semicircle to form a chamber for receiving the food product. Each machine also includes a drive system for rotating each roller. Abrasive roller peeling and cleaning machines are favored and have enjoyed considerable commercial success because they are versatile and use little, if any, water during operation minimizing post-processing water treatment costs.
During operation, each of the rollers of an abrasive roller food processing machine are rotated about a central longitudinal axis and food product entering the machine engages one or more of the rotating rollers. While in contact with a roller, the roller contacts and at least slightly abrades the food product. Each roller typically comprises a central core that has brush bristles which extend radially outwardly from the core which engage food product to wash or abrasively clean, peel, or clean and peel the food product. Other commonly used roller configurations include a roller having an exterior made of a relatively rough sandpaper-like material and a roller having a plurality of slightly axially spaced apart circular flexible rubber or plastic fins (flanges) or fingers carried by the roller core.
When cleaning food product, the rotating rollers abrade the food product to remove dirt and other residue on the food product to prepare the food product to be further processed or to enable the cleaned food product to be packaged and shipped to market. When peeling food product, the rotating rollers abrade the exterior of the food product typically to remove its skin thereby also washing or cleaning the food product. In some instances, while either cleaning or peeling food product, some water or another solvent can be introduced in the food product receiving chamber of the machine along with the food product.
In one type of abrasive roller peeling and cleaning machine, the machine comprises a frame with a pair of generally upstanding and spaced apart endplates that carry the rollers between them. The rollers are journalled for rotation in the end plates, both end plates remaining stationary during operation. Generally, the rollers are arranged in an upturned U-shaped semicircle (stationary U-bed) with very little space between each pair of adjacent rollers to prevent food product from passing between adjacent roller pairs and falling downwardly. To enable food product to flow from an inlet end to an outlet end of the machine, a rotating auger between the rollers urges food product axially relative to the rollers from the inlet toward the outlet.
In another type of abrasive roller peeling and cleaning machine, the abrasive rollers are arranged to form a cylindrical food product receiving chamber and are each journalled for rotation in the end plates which in turn are rotatably carried by the frame. More particularly, the rollers, struts and end plates form a cage that is rotated in addition to each abrasive roller being rotated. To enable food product to flow from the inlet to the outlet of the machine, the machine can be tilted downwardly in the desired direction of product flow or an auger can be received in the chamber with relative rotation between the cage and auger causing food product to be urged by the auger from the inlet end toward the outlet end of the machine.
To rotate the abrasive rollers, several types of drive mechanisms or drive systems are used. In one commonly used drive mechanism, the rollers are interconnected by belts with one of the rollers being connected to an electric or hydraulic motor by another belt. These belts simply transfer power between the rollers and transfer power from the motor to the rollers. The belts do not function as a gear reducing mechanism and therefore do not reduce the output speed of the motor to enable the rollers to handle more torque caused by a greater load on one or more of the rollers.
This relatively complicated drive mechanism is costly in construction and in maintenance. One known disadvantage to this type of drive mechanism is that all of the belt-interconnected rollers driven by a motor must all be driven at the same speed as the motor and cannot be varied in speed relative to another belt interconnected roller. Another known disadvantage to the belt drive mechanism is that belt wear during use can require time consuming and costly machine shutdowns to replace one or more worn belts. As a result of belt wear, one or more of the rollers can rotate at a speed less than the desired rotational speed which can result in incomplete peeling or cleaning of food product or which can cause the food product to have to remain longer in the chamber than desired to achieve the desired peeling or cleaning. Finally, these systems are bulky and use many moving parts, each of which decreases reliability while increasing maintenance.
In another kind of drive mechanism, each roller is driven by a hydraulic motor that is supplied with hydraulic fluid under pressure from a hydraulic pump. The motor is attached to an endplate of the peeling and cleaning machine and has an output shaft coupled to an abrasive roller. In a known U-bed stationary abrasive roller peeling and cleaning machine manufactured by Lyco Manufacturing Inc., 115 Commercial Drive, Columbus, Wis. 53925, the machine has two banks of rollers with the rollers of a given bank driven at the same speed and the roller speed and direction of one bank being variable relative to the roller speed and direction of the other bank. It is believed, and heretofore not known otherwise, that all of the rollers of a bank of rollers of the machine are not driven at exactly the same speed by the pump and motors because the motors are supplied in series with hydraulic fluid from the pump and fluid pressure losses downstream can cause downstream motors to run more slowly.
Unfortunately, without resort to relatively expensive hydraulic fluid throttling valves for each hydraulic motor, the speed of one roller in a bank cannot be selectively varied relative to another roller of the bank thereby at least somewhat limiting the versatility of the machine. Additionally, hydraulic drive systems are quite complicated and expensive to manufacture and can have reliability problems if hoses break or internal motor seals leak.
Another difficulty with hydraulic drive systems is that the hydraulic motor seals currently in use cannot typically withstand hydraulic fluid pressures of greater than about 1000 p.s.i. However, in many instances, to power in series as many as four or more rollers of a bank of rollers, an input pressure of as much as 1500 p.s.i. or greater is needed. To remedy this problem and prevent premature seal blowout, a flow divider is typically used. Unfortunately, using a flow divider results in pressure losses of as much as 150 p.s.i. or more in addition to pressure losses after each motor. All of these pressure losses accumulate resulting in a great deal of energy wasted as well as the rollers further downstream typically operating at a speed slightly slower than the speed of the upstream rolls.
In rotating cage type abrasive roller peeling and cleaning machines, either the inlet or outlet of the machine carries a hub that is driven through a belt by a motor that typically is an electric or hydraulic motor to cause the cage to rotate about a longitudinal axis of the cage. As the cage rotates, a ring-shaped stationary gear carried by the frame has inwardly extending teeth that engage a tooth of a gear at the end of each roller to drive the roller as the roller gears orbit interiorly the stationary gear. An example of this type of drive arrangement is found in U.S. Pat. No. 5,245,919.
This type of drive arrangement is rather elaborate and complicated because it uses so many moving parts to transfer rotary motion of the cage to each of the abrasive rollers. This complexity adds expense and increased maintenance. In addition to being more complicated and costly, this type of drive arrangement is limited because each of the drive rollers are driven by a single stationary gear as the cage rotates causing them all to rotate at about the same speed. As a result of being driven by a single stationary gear, none of the abrasive rollers can rotate at a different speed relative to any other roller. Moreover, the speed of all of the rollers is ultimately dependent upon the speed of rotation of the cage further limiting machine and processing flexibility.
What is needed is a drive system for an abrasive roller peeling and cleaning machine that enables each of the abrasive rollers to be driven independently of every other roller of the machine so that the speed of the rollers can be controlled and precisely varied. What is also needed is a more efficient abrasive roller drive system that provides more complete control over the entire peeling and cleaning process. What is further needed is a drive system for a rotating cage peeling and cleaning machine where the abrasive rollers are driven independently of the cage and auger. What is still further needed is a drive system for a rotating cage peeling and cleaning machine that enables the roller to be driven independently of the cage and independently of each other. What is also needed is a drive and control system for a peeling and cleaning machine that is more compact, more reliable, simpler and cheaper to manufacture and operate.